Britain's Channel 4 plans to broadcast private video tapes showing Princess Diana speaking candidly with her public-speaking coach about her failing marriage and her strained relationship with the royal family.

In an extraordinary about-face, Labor senator Sam Dastyari calls for a ban on all political donations while opening up about the scandal that cost him his seat on the Opposition frontbench, admitting he was "one of the weapons suppliers" in an "arms race" for donors' cash.